This invention relates to an improved pressure equalizing seal section also known as a protector, balance chamber or seal section (herein "equalizer") for use with a downhole electrical submersible pump.
One way of removing oil and other fluids from deep holes or wells drilled in the earth is by use of a submersible electrical pump, said pump unit which, as the name implies, is submerged in the liquid to be pumped. Submersible electrical motors employing oil as its lubricants are commonly accepted in the industry. Typically, an equalizer is located either between the pump and the motor or between the gas separator and the motor. This equalizer protects the motor oil from contamination by the well fluid, allows pressure equalization between the well annulus pressure and the motor internal pressure and connects the motor directly to the pump and provides a reservoir for volume changes as the motor heats up and cools down. These electrical motors are especially adapted for powering a pump located above and connected therethrough through coaxial spleening of their shafts. One of the characteristics of an oilfield electrical motor is that upon actuation thereof the oil lubricant becomes heated and expands upwardly along the shaft. Equalizers are interposed between the motor and the pump and having a shaft extension therein connecting the pump and the motor are well known in the industry. Various means have been devised to protect against direct contamination of the motor from either leakage of the upper seals or in event a barrier is ruptured. Perhaps the most widely used protection system is that described in U.S. Pat. No. 3,571,636. These equalizers worked well but are rather long and are thus bulky to handle.
It is therefore an object of this invention to present an improved equalizer with a novel flow path of the protecting fluid and of a compact nature.